Variable variable names for code tidy up?

Projects Programming
1

Hi there,

I am writing some code to collect data from quite a few sensors, the data will be stored in a timestamped array.

I have a nice method for collecting the data, however it seems highly inefficient on paper as I am simply copy/pasting the same piece of code 20 times (for 20 sensors), see a 2 sensor example below:

  // START Read Data S01 
  if(digitalRead(S01pin) != S01laststate)
  {
    // Prepare to pickup change next time
    S01laststate = digitalRead(S01pin);
    // Check if this is a new value or a continuation of an old reading
    if(S01timestamp[S01index] < millis() - readingdelay)
    {
      // If new reading move onto next array value
      S01index++;
    }
    S01reading[S01index]++;
    S01timestamp[S01index] = millis();
  }
  // START Read Data S02 
  if(digitalRead(S02pin) != S02laststate)
  {
    // Prepare to pickup change next time
    S02laststate = digitalRead(S02pin);
    // Check if this is a new value or a continuation of an old reading
    if(S02timestamp[S02index] < millis() - readingdelay)
    {
      // If new reading move onto next array value
      S02index++;
    }
    S02reading[S02index]++;
    S02timestamp[S02index] = millis();
  }

Could I somehow put this in it's own loop to save repeating the same piece of code 20 times?

Many thanks in advance!

2

this is perfect situation for creating a class. Create your own class library.

Create an instance for each sensor and then loop through them all in the loop function

something like

Sensor *sensor[20];

void setup() {
    sensor[0] = new Sensor(1,2,3); // some parameter into the constructor
    sensor[1] = new Sensor(2,3,4);
   ..
  .. etc
}

void loop() {
     for (var i = 0; i < 20; i++) {
         sensor[i]->doWork();
    }
}
3

No need for a class. Just put the sensor pin numbers in an array and use a for loop to read them in turn.

4

No need for a class

... but a good opportunity. You don't need to struggle with library and include files, if you don't want to.

Or use an array of structs, instead of a handful of parallel arrays for pin numbers, laststate, this and that.
A class is just a nice and convenient enhancement of a struct.

5

@michael_x: Indeed, a class is little more than a struct with functions (i.e., methods).

6

I'd use classes. THere are a bunch of private like variables he's using specific to the sensor. All he's doing now is adding a number to the variable.

7

And put the class or struct in its own .h and .cpp files.
Arduino IDE has an obscure bug that will sometimes gotcha if ya don't, or so I have read here.

8

All he's doing now is adding a number to the variable.

Crying out for an array then.

9

It's got arrays. It's crying for a loop.

Here's the Arduino IDE for-next loop example. It's stupid but it shows how for-next loops work.

/*
  For Loop Iteration
 
 Demonstrates the use of a for() loop. 
 Lights multiple LEDs in sequence, then in reverse.
 
 The circuit:
 * LEDs from pins 2 through 7 to ground
 
 created 2006
 by David A. Mellis
 modified 30 Aug 2011
 by Tom Igoe 

This example code is in the public domain.
 
 http://www.arduino.cc/en/Tutorial/ForLoop
 */

int timer = 100;           // The higher the number, the slower the timing.

void setup() {
  // use a for loop to initialize each pin as an output:
  for (int thisPin = 2; thisPin < 8; thisPin++)  {
    pinMode(thisPin, OUTPUT);      
  }
}

void loop() {
  // loop from the lowest pin to the highest:
  for (int thisPin = 2; thisPin < 8; thisPin++) { 
    // turn the pin on:
    digitalWrite(thisPin, HIGH);   
    delay(timer);                  
    // turn the pin off:
    digitalWrite(thisPin, LOW);    
  }

  // loop from the highest pin to the lowest:
  for (int thisPin = 7; thisPin >= 2; thisPin--) { 
    // turn the pin on:
    digitalWrite(thisPin, HIGH);
    delay(timer);
    // turn the pin off:
    digitalWrite(thisPin, LOW);
  }
}
10

GoForSmoke:
It's got arrays. It's crying for a loop.

yeah, you could be right.